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Air Changes Per Hour

Air Changes Per Hour

Air Changes per Hour

Determining the number of Air Changes Per Hour or (ACH) is crucial when choosing an air purification system. Which model and how many units you will need for your air purification needs? The following data has been gathered from various sources. We continually look to ASHRAE , NAFA, the EPA, and Engineering websites for newly updated clean air information. The lists below shows engineering recommendations for the number of air changes needed  in specific buildings and rooms. Your needs may vary. We also include a table on required air changes per occupant. Using these charts you should be able to determine how much air purification you need. 

Air changes can be done by bringing in fresh outdoor air or by indoor air purification.  The combination of both air purification and makeup air is often a great answer. Remember these are only recommendations.  If you need more help planning the Indoor Air Quality for your business or home, please give the experts at LakeAir a call @ 800-558-9436.

The data presented below are suggestions only. You should consult your local Government, OSHA or EPA for for any official requirements.

Building / RoomRecommended Air Changes Per Hour
All spaces in general5 min
Assembly halls6-8
Attic spaces for cooling12 – 15
Auditoriums8 – 15
Bakeries20 – 30
Banks5 – 10
Bank Vaults6
Barber Shops10 – 14
Bars20 – 30
Beauty Shops18 24
Bedrooms4 – 8
Boiler Rooms15 – 20
Bowling Alleys14 – 20
Cafeterias12 – 15
Casino (non smoking)14 – 18
Casino  (Smoking)20 – 30
Classrooms (ART)16-20
Classrooms (ages 5 and up)12 – 16
Classrooms (science lab)16 -20
Classrooms (shop classes)16 -20
Churches8 – 15
Cigar Lounges20 – 30
Club rooms12
Clubhouses20 – 30
Coin-operated dry cleaner24 -20
Coin-operated laundries11-13
Cocktail Lounges20 – 30
Computer Rooms8 -12
Commercial dry cleaner24 -30
Commercial Laundry22-26
Conference Roomos5 – 8
Court Houses4 – 10
Day Care (ages up to 4)14- 18
Dance halls16-20
Dental Centers8 – 12
Department Stores6 – 10
Dining Halls12 -15
Dining rooms (restaurants)12
Dress Shops6 – 10
Drug Shops6 – 10
Dry Cleaners6 – 20
Engine rooms4 – 6
Factory buildings, ordinary2 – 4
Factory buildings, with fumes or moisture10 – 15
Fast Food12 – 14
Fire Stations4 – 10
Food Processing10 – 25
Foundries15 – 20
Galvanizing plants20 – 30
Garages repair20 – 30
Garages storage4 – 6
Health Club20 – 26
Homes, night cooling10 – 18
Hookah20 – 30
Hospital rooms6 – 10
Kitchens (commercial)15 -30
Kitchens ( residential )8 -14
Laundries10 – 15
Libraries, public5
Lunch Rooms12 -15
Luncheonettes12 -15
Nightclubs20 – 30
Machine shops6 – 12
Malls6 – 10
Meat Processing20-26
Medical Centers8 – 12
Medical Clinics8 – 12
Medical Offices8 – 12
Mills, paper15 – 20
Mills, textile general buildings5
Mills, textile dye houses15 – 20
Money Counting room8 – 15
Municipal Buildings5 – 10
Museums (Childrens)12 -15
Museums / Galleries10-14
Nail Salons18 -24
Offices, public5
Offices, private5
Photo dark rooms10 – 15
Pharmacy Prep8 – 10
Pig houses6 – 10
Pet Shops12 – 14
Photo Studios6 – 8
Police Stations5 – 10
Post Offices5 – 10
Poultry houses6 – 10
Precision Manufacturing10 – 50
Public Retail Stores6 – 10
Pump rooms5
Residences4 – 6
Restaurants8 – 12
Retail6 – 10
School Classrooms4 – 12
Shoe Shops6 – 10
Shopping Centers6 – 10
Shops, machine5
Shops, paint15 – 20
Shops, woodworking5
Smoking Lounges20-30
Substation, electric5 – 10
Supermarkets8 – 10
Swimming pools20 – 30
Town Halls5 – 10
Taverns (non smoking)14-18
Taverns (Smoking)20 – 30
Theaters8 – 15
Transformer rooms10 – 20
Turbine rooms, electric5 – 10
Vape Shop20 – 30
Warehouses6 – 30
Waiting rooms, public5
Welding Areas12-16


Type of Building and Room  OccupantCFM
AnimalsSheepCFM per Animal6
HorsesCFM per Animal85
HensCFM per Animal6
CowsCFM per Animal212
ChickensCFM per Animal4
Pigs, sowCFM per Animal127
PigletCFM per Animal32
Apartments CFM per Person32
Assembly halls CFM per Person21-32
Auditoriums CFM per Person21-32
BakeriesProductionCFM per Person32-42
Pastry roomCFM per Person32-42
BanksServiceCFM per Person21-32
ArchiveCFM per Person15-21
StaffCFM per Person21-32
Baths CFM per Person32
Barber Shops CFM per Person21-32
Bars CFM per Person32-42
Beauty Shops CFM per Person21-32
Bedrooms4 – 8
Cafeterias CFM per Person21-32
Cinemas/Theaters CFM per Person15-21
Chemist’s shopsSterile roomCFM per Person42-53
LaboratoryCFM per Person42-53
Packing roomCFM per Person21-32
StoreCFM per Person15-21
Churches CFM per Person21
Clubhouses CFM per Person32-42
Cocktail Lounges CFM per Person32-42
Computer Rooms CFM per Person21-32
Court Houses CFM per Person21-32
Dance halls CFM per Person32-42
Dental Clinics, Offices CFM per Person21-32
Department Stores (cfm/Sq.Ft) CFM per Person21-32
Dining Halls CFM per Person21-32
Drug Store CFM per Person21-32
Engine rooms CFM per Person21-32
Exhibition halls CFM per Person21-32
Fire Stations CFM per Person21-32
Garages CFM per Person21-32
HospitalsGeneralCFM per Person32
TherapyCFM per Person21-32
Operating theaterCFM per Person42-64
AutopsyCFM per Person32
HotelsReceptionCFM per Person32-42
RoomCFM per Person21-32
IndustriesFactoryCFM per Person21-42
Carpenter work shopCFM per Person21-32
Car repair shopCFM per Person21-32
Car repair shop, exhaust outletCFM per Car127-170
Mechanical work shopCFM per Person32-42
WeldingCFM per Person42
AssemblyCFM per Person21-32
Jails CFM per Person21-32
Jewelry Shop CFM per Person21-32
Libraries CFM per Person21-32
Lunch Rooms, Luncheonettes CFM per Person21-32
Municipal Buildings CFM per Person21-32
Museums CFM per Person21-32
Laundries CFM per Person32-42
Lavatories CFM per Person21
Night Clubs CFM per Person32-52
Malls CFM per Person21-32
Motels CFM per Person32-42
OfficesModuleCFM per Person21-42
LandscapeCFM per Person21-42
Conference roomCFM per Person62-64
Lecture roomCFM per Person21-42
Dining hallCFM per Person32-53
Staff, changing clothesCFM per Person21-32
Dining roomCFM per Person32
Resting roomCFM per Person32
Police Stations CFM per Person21-32
Post Offices CFM per Person21-32
Precision Manufacturing CFM per Person21-32
Restaurants CFM per Person21-32
Retail Stores (cfm/Sq.Ft) CFM per Person21-32
SchoolsClassroomCFM per Person21-32
Shops CFM per Person21-32
Shopping Centers CFM per Person21-32
Sports halls CFM per Person32-42
Supermarkets CFM per Person21
Swimming pools CFM per Person32
Taverns CFM per Person21-32
Town Halls CFM per Person21-32

Frequently Asked Questions

The air change rate is a measure of how often the air in a room is replaced with fresh air. It is usually expressed as the number of times the air is completely replaced in an hour. For example, an air change rate of 1 means that the air in the room is completely replaced once every hour.

The air change rate is important because it affects the amount of fresh air that is available for people to breathe.

The ideal air change rate is the rate at which air is exchanged between indoor space and the outdoors. It is typically expressed as the number of times per hour that the air in a space is completely replaced with fresh air from outside.

The ideal air change rate depends on a number of factors, including the size of the space, the number of people occupying it, the level of activity taking place, the type of ventilation system in place, and the climate.

The air change rate is important because it determines how often the air in a room is replaced with fresh air. The higher the air change rate, the more often the air is replaced and the fresher it will be. The air change rate is also important because it affects the efficiency of heating and cooling systems. A higher air change rate means that the system will have to work harder to maintain the desired temperature, which can lead to higher energy bills.

There are a few ways to measure air change rate, the most common being to use an anemometer. This is a device that measures the speed of airflow. To use an anemometer, you simply hold it in the air and wait for the needle to stabilize. The reading on the anemometer will tell you the air change rate.

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